The most prevalent methods for inserting insulation material into winter garments generally involve filling the garments with loose insulating material. For example, winter coats filled with down material throughout the body portion and sleeves are well known. Similarly, various polyester fibers may be used in place of the down. Such garments are bulky and tend to limit one's freedom of movement. Also, the loose fibers shift, settle, mat and are difficult to work with. Further, their insulating characteristics are drastically reduced if they are wet.
More recently, composite sheets of thermal insulating material have been employed to produce less bulky, looser winter garments. A composite thermal insulating interlining sheet material of the type which is the subject of the present invention is disclosed in U.S. Pat. No. 4,136,222.
U.S. Pat. No. 4,136,222 relates to a thermally insulating composite sheet material which may be used as an interlining material for garments, blankets, etc. The composite sheet material of this patent comprises at least one thin lightweight drapable sheet carrying a vapor-deposited layer of specularly reflective material on at least one surface, and a layer of segments of insulating material, which segments cover preferably between about 10 percent and 30 percent of the area of the layer of specularly reflective material up to a maximum of 60 percent of such area. The area of the layer of insulating material is minimized to provide as great an open area as possible ranging from 40 percent to as high as 90 percent so that the reflecting layer will be utilized most efficiently to reflect heat back to the body of the wearer, i.e., body heat radiated in the form of infrared radiation is reflected. Although the disclosure of U.S. Pat. No. 4,136,222 makes reference to the low emissivity of the specularly reflective layer, it stresses the reflective feature of such layer and, in fact, notes that use of a fibrous spacer (rather than spacer segments) would take away much of the function of the specularly reflective layer. Thus, the layer of insulating material is used principally as a spacer means rather than for the insulating qualities of its material, so as to permit, in use, direct and substantially unimpeded exposure of the specularly reflective layer to infrared radiation emitted from the body of the wearer which can then be reflected back. In other words, the spaced, large openings are deemed necessary in the interlining material of U.S. Pat. No. 4,136,222 to achieve the reflection, and thus insulating, characteristics of the insulating composite sheet material. However, the need for spaced, large openings in the spacer layer of the '222 patent results in complex manufacturing techniques and increased cost per yard of the final product.
The use of reflective layers of material for providing protection against extreme cold is known, as is evidenced, for example, by U.S. Pat. No. 3,849,802 which relates to a temperature protective suit comprising a strong fabric coated on both sides with a thin layer of heat-reflective metal. This patent discloses that, in the alternative, there may be a metallic coating on only one layer. The fabric, however, is not suited for or intended to be used as an interlining material for garments and the like. Rather, the invention therein is directed to a reversible temperature protective garment for the preservation and protection against heat and cold. The reflectivity of the metallic coating is utilized to preserve body heat when heat is to be retained. In such event, the shiniest side is on the inside. Thus, as in the product of U.S. Pat. No. 4,136,222, reflection of the body heat is the predominant characteristic to maintain body warmth. Therefore, when heat resistance is desired, the shiniest side is disposed on the outside.
The use of a continuous layer or layers of insulating material in a composite insulating fabric is taught in U.S. Pat. No. 3,541,620 which discloses a fabric which includes juxtaposed thin layers of polyurethane foam and polystyrene in combination with a waterproof material. The resultant waterproof fabric is particularly suited for sleeping bags and the like.